Internal GNSS configuration

Doc for Ellipse firmware < 3.0

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This brief document will guide you through the process of configuring the internal GNSS receiver for your Ellipse that have an embedded GNSS.

If your integration involves using an external GNSS receiver, please refer to the How to integrate an external GNSS receiver section.

Step 1 : INS configuration

In order to configure the INS, you need to connect to the sbgCenter and open the configuration window. Simply follow those instructions:

Set aiding assignment

In this window, you just select the Internal option for the GNSS 1 source, and it will automatically select the internal PPS as the Sync source.

Set correct GNSS model and configuration

1. GNSS model should be set to "Internal" by default and cannot be changed when selecting the internal GNSS receiver in the Aiding Assignment window.

2. GNSS lever arms are to be measured with 5 cm accuracy FROM the IMU TO the antenna phase center (APC), in the vehicle frame. If the option “The primary antenna lever arm has been measured precisely” is ticked, then the Extended Kalman filter will take these values for granted and will not estimate any values for this Primary antenna lever arm. It should help the system to align faster, but in this case, the Primary antenna lever arms must be measured within 1 cm accuracy.

3. In case of Dual antenna system, the secondary antenna lever arm must also be entered FROM the IMU TO the antenna phase center (APC), and the same accuracy requirements as for the primary antenna apply, depending if the above selection box is set to "Precise" or "Rough" lever arm value.

4. Finally, each available measurement (position, velocity, and heading if available i.e. if using a dual antenna receiver) should be configured to be used or not. Automatic is recommended.

Check clock alignment

Finally, you check that the time synchronization reference is set to GPS 1 (default configuration).

Step 2 : Checking status

The device status and GNSS windows should be checked carefully before proceeding further. These status indicators will give essential hints in case of troubles to get a correct fix. Each step is labeled in red in the following screenshot.

1. GNSS 1 frame in “Aiding Inputs” tab must show that the data is received.

2. After that, you can check if the GNSS solution has been calculated and is consistent in the GNSS 1 window.

3. Then you can check the "Clock" section. Input clock must be OK and UTC time should be set to valid after a few minutes in steering mode.